Circuit interrupter



Oct. 7, 1947. H. M. wlLcox ETAL CIRCUIT INTERRUPTER Filed Feb. 28, 1945 4 Sheets-Sheet 1 INVENTORS' Howard/14 h/f/cox onc/ WITNESSES: 62 4 2d,

Pay/n and/i Aehze 6i lTTORN EY 7 Oct. 7, 1947. H. M. WILCOX ETAL CIRCUIT INTERRUPTER Filed Feb. 28, 1945 4 Sheets-Sheet 2 INVENTORS Howard/14 Mkoxana Pay/hand Lehze/ BY lq ATTORNEY WITNESSES:

4 Sheets-Sheet 3 INVENTORS Howard/14. M/cox and. Eaymond H. leffze ATTORNEY H. M. WILCOX EFAL CIRCUIT INTERRUPTER Filed Feb. 28, 1945 Oct. 7, 1947.

Patented Oct. 7, 1947 UNITED STATES PATENT OFFICE CIRCUIT INTERRUPTER Application February 28, 1945, Serial No. 580,138

'22 Claims. (Cl.200--148) This invention relates to circuit interrupters, in general, and, more particularly, to circuit interrupter-s of the gas blast type in which the gas is used to effect, by blast action, extinction of the are drawn within the circuit interrupter,

A general object of our invention is to provide an improved circuit interrupter of the gas blast type in which improved operation of the blast valve is obtained to more readily effect the extinction of the arc inthe circuit interrupter than has heretofore been obtained.

Another object is to provide an improved circuit interrupter of the gas blast type in which th mechanism, which is utilized to open the contacts and to effect operation of the blast valve, is of improved and high-speed construction.

Another object is to provide a very rapid highspeed operating mechanism for a circuit interrupter of the gas blast type in which operation of the blast valve is synchronized with contact opening and also in which high-speed operation of the blast valve is obtained.

Further objects and advantages wil readily become apparent upon a reading of the following specification taken in conjunction with the drawings, in which Figure 1 is a side elevational view of a gas blast type of circuit interrupter embodying our invention and shown in the closed circuit position.

Fig. 2 is an enlarged fragmentary view of the improved operating mechanism of our invention, the parts being shown in the closed circuit positlon of the interrupter.

Fig. 3 is a fragmentary view showing the position of the operating mechanism at an intermediate point in th opening operation.

Fig. 4 is a fragmentary view of the position of the operating mechanism in the fully open circuit position of the interrupter.

Fig. 5 is a fragmentary plan view of a portion of the operating mechanism, and

Figs. 6 and 7 show a modified form of the mechanism.

Referring to the drawings, and more particularly to Fig. 1 thereof, the reference numeral I designates a tank of compressed gas, in this instance compressed air, which supports a conduit 2, the latter leading to another conduit 3 passing into a valve casing 4 leading to a blast tube 5. The blast tube 5 serves to conduct an arc-extinguishing blast of gas from the tank I by operation of a blast valve mechanism 6 to the are drawn between the movable contact 1 and the stationary contact structure 8. A line terminal 9 is electrically connected to the movable con- 2 tact l, and a second line terminal I0 is electrically connected to the stationary contact structure 8.

Consequently, in the closed circuit position of the interrupter, as shown in Fig. 1, the electrical circuit theret'hrough comprises line terminal 9, movable contact 1, stationary contact structure 8, to the other line terminal i0. Upon separation of the movable contact 1 from the stationary contact structure 8, an arc is drawn therebetween which is extinguished by a blast of gas passing upwardly through the blast tube 5 to force the arc into the arc chute structure, generally designated by the reference numeral H. Th are chute structure H may be of any suitable type and forms no part of our invention. Preferably, the arc chute structure II is of the type described and claimed in United States Patent 2 272,380, which issued February 10,, 1942, to Leon R. Ludwig, Herbert L. Rawlins and Benjamin P. Baker, and which is assigned to the assignee of this application.

In the circuit interrupter of our invention, two of the tanks 1 are provided, only one being shown in Fig. 1. Between these two tanks l is a pair of supporting side plates I2 spaced relatively closely to one another and rigidly secured together. These two supporting side plates 12 support thereoetween the operating mechanism for the interrupter as more clearly shown in Fig. 2. The side plates l2 and the tanks 1 are, in turn, supported by a suitable framework of rigid construction, not shown, which is preferably disposed within a weatherproof housing, also not shown.

Referring to Fig. 2, the reference numeral 13 generally designates a magnetic closing valve which governs the operation of a closing valve [4, which, in turn, controls the admission of com pressed gas from an inlet conduit l5 to an operating cylinder It in which slidably moves a piston Mia. The piston Ilia operating within the cylinder I6 is connected to a piston rod H which moves a crosshead IS, the latter being guided by the slots 19 provided in a bifurcated casting member 20 suitabiy secured to the end 2| of the operating cylinder I6.

The crosshead I8 is pivotally connected by a short link 2?. to a bell crank 23 pivotally mounted at a fixed pivot 24, the fixed pivot 24 being provided by an upstanding portion 25 of the castin member 20. The upper end of the bell crank 23, designated by the reference numeral 26, constitutes one leg of a toggle, generally designated by the reference numeral 21, having a knee-pin 28 and upper links 29 which are pivotally connected at 30 to a first operating part consisting of two nrst levers 3|. An adjustableover-center toggle s;op 53a is provided.

'rne nrst operating part or first two levers 3| ar pivotally mounted on stationary pivots 32 seated in the support plates 12.

lavotally mounted to the first levers 3| on the pin 33 is a second operating part or trip i'ree lever 33. The left-hand end of the second lever 33 is latched by a latch mechanism generally designated by the reference numeral 34 and released by rotation of a trigger 35, the latter being pivotall mounted about a stationary pivot 36. The trigger 35 may be rotated about the stationary pivot 36, either manually or by electrical means such as the solenoid 35a, actuated in response to designated current conditions existing in the circuit controlled by the interrupter.

An insulating operating rod 31 (Fig. 1), having its upper end pivotally connected at 38 to the movable contact I has its lower end threadedly secured to a metallic U-shaped member 39, the lower end of WlliCh is biluicated as at 33a and is pivotally mounted to the right-hand end of the second lever at 43, more clearly shown in Fig. 2. Also connected to the second lever 33, at 43, is an opening accelerating mechanism, generally designated by the reference numeral 4|, and comprising a link 32 and an operating rod 4.3 movable within a cylinder 44, housing a battery of compression springs 45 which serve to bias the operating rod 43 downwardly to effect opening operation of the interrupter.

rhe blast valve mechanism 6 comprises a blast valve 45 having a stem 41 pivotally secured to an actuating member 48 at 43. The actuating member 48 is pivotally mounted at 50 to the wall of the valve casing 4 and has two externally extending operating legs 52 which support a pin 53 upon which is mounted a roller 53a thereon.

In the closed circuit position of the interrupter, as shown in Fig. 2, a third cam portion 54 of the second operating part 33 comes closely adjacent to the first cam portion of the leg 52 or roller 53a, the purpose for which will appear more clearly hereinafter.

The blast valve mechanism, although herein simplified, is preferably of the adjustable roller type shown in United States Patent 2,310,779 which issued February 9, 1943, to Erik H. Hall and Raymond H. Leitzel, which is assigned to the assignce of the instant invention.

The operation of the interrupter will now be explained. In the closed circuit position of the interrupter, the parts assume a position as shown in Figs. 1 and 2. To effect an opening of the contact structure, the trigger 35 is rotated in a counterclockwise direction about the pivot 36 by energizing the solenoid 35a to effect release of the latching mechanism 34. The release of the latching mechanism 34 permits the second operating part 33 to rotate in a clockwise direction about the piVotal connection to the first operating part 3| at 35. This motion of the second operating part 33 results because of the biasing action exerted by the compression springs 45 which tend to bias the second operating part 33 in a clockwise direction about the pivot point 33.

During the release of the latch mechanism 34 and the consequent clockwise rotation of the second lever 33 about the pivot 33, the first operating part 3| remains stationary, as shown in Fig. 3. Thrs, the second lever 33 rotates to the position shown in Fig. 3 before any movement 4 of the first operating part 3| results during the opening operation.

Following the clockwise rotation of the second lever 33, as shown in Fig. 3, the toggle 2'! is collapsed by a kick-off device 55, comprising a rod 55a linked at 551) to the bell crank 23 and biased to the right by the compression springs 550. More specifically, when the tension on the part 3| has been relieved by rotation of the lever 33 to open circuit position, the springs 55c exert a force sufiicient to move the toggle 27 to the right from its extended overcenter position, rotating the first operating part 3| in a clockwise direction about its stationar pivot 32 to permit collapse of the toggle 2'! as more fully shown in Fig. 4.

During this collapse of the toggle 21 to effect clockwise rotation of the first operating part 3| about the stationary pivot 32, the second operating part 33 rotates in a counterclockwise direction about the pivot 40 until the left-hand end of the second or trip-free lever 33 is again latched by the latch mechanism 34. Meanwhile, the piston |5a within the operating cylinder Iii has been forced to its leftward position by the biasing means 56 associated with the kick-off toggle rod 55 and comprising the two compression springs 550. The fully open circuit position of the interrupter is shown in Fig. 4.

It will be observed that the initial clockwise rotation of the second lever 33 caused the third cam portion 54 thereof to engage the first cam portion of the leg 52 or roller 53a thereby causing counterclockwise rotation of the legs 52 about the pivot 53, thus efiecting opening motion of the blast valve 45. The opening motion of the blast valve 46 at this time permits an arc-extinguishing blast of gas to pass from the tank I upwardly through the valve mechanism 6, upwardly through the blast tube 5 to extinguish the are drawn by the movable contact 1 and the stationary contact structure 8.

Following predetermined rotative travel of the second lever 33, the cam portion 54 rides off of the roller 53a to permit the compression spring 5'! to effect closure of the blast valve 46.

During the closing operation, the magnetic closing valve I3 is operated electrically to permit operation of the valve structure within the closing valve l4 to permit compressed air to pass from the conduit l5 through the closin valve l4 to the left-hand end of the operating cylinder Hi to effect thereby rightward movement of the piston IBa within the cylinder Hi. This effects rightward travel of the piston rod IT to effect counterclockwise rotation of the bell crank 23 about the stationary pivot 24 to cause extension of the toggle 21 and counterclockwise rotation simultaneously of both the first and second operating levers 3| and 33 about their concentric axis of rotation 32. This movement effects upward motion of the operating rod 31 to bring about contact closure and simultaneously effects compression of the compression springs 45. During the complete closing operation, the second operating part or second lever 33 remains latched by the latching mechanism 34. It is only during the opening operation that the latch mechanism 34 is operated.

Since the second lever 33 is relatively light and is strongly biased by the compression springs 45 about the pivot 3|], high-speed opening clockwise rotation of the second lever 33 results when the latter is unlatched by operation of the latch mechanism 34. As stated previously, during the unlatching movement of the second lever 33, the first lever, the toggle and the piston, which are relatively heavy, remain stationary and do not slow down or in any way effect the contact opening movement.

From the foregoing description of our invention, it will be apparent that we have provided an improved high-speed operating mechanism for a circuit interrupter of the compressed gas type in which quick opening movement of the contact structure results, and in which the opening of the blast valve is synchronized with opening movement of the movable contact. During the closing movement of the second lever 33, the blast valve remains closed. It will also be apparent that the mechanism is simple in construction, having few movable parts and in which the closing operation effects compression of the accelerating springs 45 to strongly bias the contact structure to the open circuit position.

It will be observed that following unlatching of the second lever 33, there is required relatively little force to effect collapse of the toggle 2i, and that in the closed position the compressive force of the accelerating springs 45 maintains the toggle 2! in its overcenter position against the relatively weak biasing action exerted by the biasing means 56 of the kick-off toggle rod 55.

In the blast valve mechanism shown in Figs. 1 through 5 inclusive, it is necessary for the contacts to become completely closed in overlapping relation as shown in Fig. 1 before the breaker may be opened. Thus, even though the breaker is closed in on a fault, nevertheless, the contacts must completely come to their fully closed position before it is possible to reverse the contact motion and, hence, open the blast valve to extinguish the are drawn between the contacts 1', 8.

Figs, 6 and 7 show a modification of our invention which is especially useful in a breaker in which the electrical circuit is such that reversal of contact motion during a closing operation when closing on a fault is permitted. In other words, the modification of our invention shown in Figs. 6 and '7 permits reversal of contact motion during the closing operation before the contacts have arrived at the fully closed position.

For example, assume that the breaker shown in Figs. 6 and 7 is closed in on a fault. When the movable contact I is, say, two or three inches away from the stationary contact 8, the voltage may be sufficient to cause fiasho-ver between the contacts I, 8 during such a closing operation when closing in on a fault. The resulting flashover between the contacts I, 8 when they are separated two or three inches, will be sufficient to trip the electrical circuit to thereby trip the latch mechanism 34. Since the cam portion 54 only raises the roller 53a of an inch in the construction shown in Fig. 2, it is apparent that the pivot 39 would not be in a sufliciently raised position during such a closing operation to permit engagement between the cam surface 54 and the roller 53a to cause opening of the blast valve 46.

However, in the arrangement shown in Figs. 6 and 7, the operatin legs 58, which support a pin 53 upon which is mounted the roller 53a forming a first cam portion, also are extended to form a cam surface 59 forming a second cam portion which engages a pin 60, the latter extending transversely across the second operating part 33 to form a fourth cam portion. Thus, should the second operating part 33 be unlatched by the latch mechanism 34 during a closing operatic-n,

when closing in on a fault, to cause clockwise rotation of the second or trip-free lever 33, then even though the pivot 30 is not positioned upwardly high enough to permit engagement of the cam portion 54 with roller 53a, nevertheless, at this time the pin 68 or fourth cam portion will engage the cam surface 59 or second cam portion of the two legs 58 to cause opening of the blast valve 46.

From the foregoing it will be apparent that during the normal opening operation from the completely closed overlapping position of the .contacts l, 8, the third cam portion 5% may be relied upon to open the blast valve it, the pivot 33 being positioned high enough for this purpose, and the first cam portion or roller 53a bein raised approximately of an inch. During abnormal opening operations, that is resulting from a reversal of contact motion durin a closing operation, when closing in on a fault, and even before the contacts I, 8 have engaged the fourth cam portion or pin Bil will engage the second portion or cam surface 59 of operating legs 5.8 to cause counterclockwise rotation of the operating legs 58 about the pivot 5E3 to thereby cause opening of the blast valve 45. The cam surface 59 is so formed that immediately upon the unlatching of the second operating part 33 and, hence, clockwise rotation of the same about the pivot 30, the pin 60 will engage the cam portion 54 to im" mediately, without any delay, cause opening of the blast valve 46 to permit compressed air to pass upwardly through the blast tube 5 to extinguish the arc drawn between the contacts 1, 8.

' Fig. 6 shows the position of the parts when the first operating levers 31 are not raised to their fully closed circuit position as shown in Fig. :2, and in which the second or trip-free lever 33 has been unlatched and rotated slightly to cause simultaneously contact separation and opening of the blast valve 46 by engagement of the pin 166 with the cam portion 59. Consequently, in Fig, 6 the pivot 30 is below that which is shown in Figs. 2 and 3.

Thus, Figs. 6 and '7 show amodification of our invention suitable for application to breakers having such an electrical circuit that reversal of contact motion during a closing operation is permitted even before the contacts arrive at the fully closed circuit position.

Certain features of the toggle rod 55 are described and claimed in a concurrently filed application by Benjamin P. Baker and Donald C. Harker, Serial No. 580,136, entitled Circuit interrupter, and assigned to the assignee of this application.

Although we have shown and described a specific structure, it is to be clearly understood that the same was merely for the purpose of illustration and that changes and modifications may readily be made therein by those skilled in the art without departing from the spirit and scope of the appended claims.

We claim as our invention:

1. In a circuit interrupter, a first operating part, means pivotally mounting the first operating part, means causing the rotation of the first operating part during the closing operation of the interrupter, a second operating part, a movable contact, means interconnecting the second operating part and the movable contact, means pivotally mounting the second operating part to the first operating part, latching means for the second operating part, a blast valve, and the secnd operating part having a cam surface to operate the blast valve.

2. In a circuit interrupter, a first operating part, means pivotally mounting the first operating part, means causing the rotation of the first operating part during the closing operation of the interrupter, a second operating part, a movable contact, means interconnecting the second operating part and the movable contact, means pivotally mounting the second operating part to the first operating part, latching means for the second operating part which latches the second operating part at a point which is on a centerline of the axis of rotation of the first operating part, a blast valve, and the second operating part having a cam surface to operate the blast valve.

3. In a circuit interrupter of the gas blast type, a first operating lever, means pivotally mounting the first operating lever adjacent one end thereof, means causing the rotation of the first operating lever during the closing of the interrupter, a second operating lever, a movable contact, means interconnecting the movable contact with the second operating lever, means pivotally mounting the second operating lever to the first operating lever, latching means for the second operating lever, a blast valve, and the second operating lever having a cam portion to operate the blast valve.

4. In a circuit interrupter of the gas blast type, a first rotatable operating means, means pivotally mounting the first rotatable operating means, second rotatable operating means, means pivotally mounting the second rotatable operating means to the first rotatable operating means, contact means, means connecting the contact means to the second rotatable operating means, latching means for the second rotatable operating means for latching the latter on a centerline with the pivotal mounting for the first rotatable operating means, a blast valve for controlling the flow of gas under pressure, and means interrelating unlatching movement of the second rotatable operating means With operation of the blast valve.

5. In a circuit interrupter, a first operating part, means pivotally mounting the first operating part, means causing the rotation of the first operating part during the closing operation of the interrupter, a second operating part, a movable contact, means interconnecting the second operating part and the movable contact, means pivotally mounting the second operating part to the first operating part, latching means for the second operating part, a blast valve for controlling the flow of gas under pressure, and means interreiating unlatching motion of the second operating part with operation of the blast valve.

6. In a circuit interrupter of the gas blast type, contact means for establishing an arc, a source of gas under pressure, a blast valve for controlling the flow of the gas under pressure, a first lever, means pivotally mounting the first lever adjacent one end thereof, a second lever, means pivotally mounting the second lever to the first lever, means latching the second lever on a center-line of rotation of the first lever, means interconnecting the contact means to the second lever at a point thereof spaced from the point of mounting thereof to the first lever and opposite the point of latching, means interrelating unlatching motion of the second lever with opening movement of the blast valve.

'7. In a circuit interrupter of the gas blast type, contact means for establishing an are, a source of gas under pressure, a blast valve for controlling the flow of the gas under pressure, a first lever, means pivotally mounting the first lever adjacent one end thereof, a second lever, means pivotally mounting the second lever to the first lever, means latching the second lever on a centerline of rotation of the first lever, means interconnecting the contact means to the second lever at a point thereof spaced from the point of mounting thereof to the first lever and opposite from the point of latching, means interrelating unlatching motion of the second lever with opening movement of the blast valve, and operating toggle means for operating the first lever and connected thereto at the point of mounting of the second lever.

8. In a circuit interrupter, a first operating part, means pivotally mounting the first operating part, means causing the rotation of the first operating part during the closing operation of the interrupter, a second operating part, a movable contact, means interconnecting the second operating part and the movable contact, means pivotally mounting the second operating part to the first operating part, latching means for the second operating part, a blast valve, the second operating part having a cam surface to operate the blast valve, and biasing means for biasing the movable contact to the open circuit position and acting on the second operating part at the point thereof to which the movable contact is connected.

9. In a circuit interrupter, a first operating part, means pivotally mounting the first operating part, means causing the rotation of the first operating part during the closing operation of the interrupter, a second operating part, a movable contact, means interconnecting the second operating part and the movable contact, means pivotally mounting the second operating part to the first operating part, latching means for the second operating part which latches the second operating part at a point which is on a centerline of the axis of rotation of the first operating part, a blast valve, the second operating part having a cam surface to operate the blast valve, and biasing means for biasing the movable contact to the open circuit position and acting on the second operating part at the point thereof to which the movable contact is connected.

10. In a circuit interrupter of the gas blast type, a first operating lever, means pivotally mounting the first operating lever adjacent one end thereof, means causing the rotation of the first operating lever during the closing of the interrupter, a second operating lever, a movable contact, means interconnecting the movable contact with the second operating lever, means pivotally mounting the second operating lever to the first operating lever, latching means for the second operating lever, a blast valve, the second operating lever having a cam portion to operate the blast valve, and biasing means for biasing the movable contact to the open circuit position and acting on the second operating part at the point thereof to which the movable contact is connected.

11. In a circuit interrupter of the gas blast type, a first rotatable operating means, means pivotally mounting the first rotatable operating means, second rotatable operating means, means pivotally mounting the second rotatable operating means to the first rotatable operating means, contact means, means connecting the contact means to the second rotatable operating means,

latching means for the second rotatable operatingmeans for latching the latter on a centerline with the pivotal mounting for the first rotatable operating means, a blast valve for controlling the flow of gas under pressure, means interrelating unlatching movement of the second rotatable operating means with operation of the blast valve, and biasing means for biasing the movable contact to the o en circuit position and acting on the second operating part at the point thereof to which the movable contact is connected.

12. In a circuit interrupter, a first Operating part, means pivotally mounting the first ope-rating part, means causing the rotation of the first operating part during the closing operation of the interrupter, a second operating part, a movable contact, means interconnecting the second operating part and the movable contact, means pivotally mounting the second operating part to the first operating part, latching means for the second operating part, a blast valve for controlling the flow of gas under pressure, means interrelating unlatching motion of the second operating part with operation of the blast valve, and biasing means for biasing the movable contact to the open circuit position and acting on the second operating part at the point thereof to which the movable contact is connected.

13. In a circuit interrupter of the gas blast type, contact means for establishing an arc, a source of gas under pressure, a blast valve for controlling the flow of the gas under pressure, a first; lever, means pivotally mounting the first lever adjacent one end thereof, a second lever, means pivotally mounting the second lever to the first lever, means latching the second lever on a center-line of rotation of the first lever, means interconnecting the contact means to the second lever at a point thereof spaced from the point of mounting thereof to the first lever and opposite the point of latching, means interrelating unlatching motion of the second lever with opening movement of the blast valve, and biasing means for biasing the movable contact to the open circuit position and acting on the second operating part at the point thereof to which the movable contact is connected.

14. In a circuit interrupter of the gas blast type, contact means for establishing an arc, a source of gas under pressure, a blast valve for controlling the flow of the gas under pressure, a first lever, means pivotally mounting the first lever adjacent one end thereof, a second lever, means pivotally mounting the second lever to the first lever, means latching the second lever on a center-line of rotation of the first lever, means interconnecting the contact means to the second lever at a point thereof spaced from the point of mounting thereof to the first lever and opposite the point of latching, means interrelating unlatching motion of the second lever with opening movement of the blast valve, operating toggle means for operating the first lever and connected thereto at the point of mounting of the second lever, and biasing means for biasing the movable contact to the open circuit position and acting on the second operating part at the point thereof to which the movable contact is connected.

15. In a circuit interrupter of the gas blast type, contact means, operating means for effecting closure of the contact means, trip-free means comprising a pivotally mounted trip-free lever, means at all times connecting said trip-free lever to said operating means, means for latching the trip-free lever adjacent one end thereof, means 10 interconnecting the contact means with the other end of the trip-free lever, a blast valve, and a portion of the trip-free lever causing opening of the blast valve during opening movement of the lever.

16. In a ircuit interrupter of the gas blast type, a stationary contact, a movable contact separable from the stationary contact to establish an arc therebetween, operating means for moving the movable contact to closed contact position, trip-free means comprising a releasable member, means at all times pivotally interconheating the operating means with the releasable member, means interconnecting the movab7e contact with the releasable member, means for latching the releasable member adjacent one end thereof, a blast valve, and means actuated by opening motion of the releasable member for effecting opening of the blast valve.

1'7. In a circuit interrupter of the gas blast type, a blast valve, an actuating arm for the blast valve, means pivotally mounting the actuating arm, the actuating arm having a first cam portion and a second cam portion, trip-free means comprising a member, operating means, means pivotaly interconnecting the operating means with the member, the member having a third cam portion and a fourth cam portion, means for latching the member adjacent one end thereof, a movable contact, means operativelv interconnecting the movable contact with the member, thev arrangement operating during normal opening operations to cause engagement of the first cam portion with the third cam portion and operating during abnormal opening operations to cause engagement of the second cam portion with the fourth cam portion.

18. In a circuit interrupter of the gas blast type, a stationary contact, a movable contact separable from the stationary contact to establish an arc, a blast valve, an actuating arm for the blast valve, means pivotally mounting the actuating arm, the actuating arm having a first cam portion including a roller and a second cam portion, trip-free means comprising a member, operating means, means pivotally interconnecting the operating means with the member, mean-s for latching the member adjacent one end thereof, means interconnecting the movable contact with the other end of the member, the member having a third cam portion and a fourth cam portion, the fourth cam portion including a transversely extending pin, the arrangement operating during normal opening operations to cause engagement between the first and third cam portions and during abnormal opening operations engagement between the third and fourth cam portions.

19. In a circuit interrupter of the gas blast type, separable contact means for establishing an arc, a blast-valve for controlling the flow of gas under pressure, and operating means for said contact means and said blast-valve comprising a first member pivotally mounted for rotative movement between two predetermined positions, means including an overcenter toggle for actuating said member to and retaining it in one of said positions, a second member pivotally mounted upon said first member for rotative movement independently of said first member, means interconnecting said second member and said contact means whereby rotation of said second member imparts movement to said contact means, means for latching said second member to prevent relative rotation between said members, and means associated with said second member operative upon rotation of said second member to actuate said blast-valve when said first member is in said one position.

20. In a circuit interrupter of the gas blast type, separable contact means for establishing an arc, a blast-valve for controlling the flow of gas under pressure, and operating means for said contact means and said blast-valve comprising a first member pivotally mounted for rotative movement between two predetermined positions, means including an overcenter toggle for actuating said member to and retaining it in one of said' positions, a second member pivotally mounted upon said first member for rotative movement independently of said first member, means interconnecting said second member and said contact means whereby rotation of said second member imparts movement to said contact means, means for latching said second member to prevent relative rotation between said members, and at least two blast-valve actuating devices associated with said second member one of which is operative upon rotation of said second member only when said first member is in said one position and the other device being operative only upon rotation of said second member when said first member is in a position intermediate said two positions.

21. In a circuit interrupter of the gas-blast type, a stationary contact, a movable contact separable from the stationary contact to establish an are, a blast valve, a pivoted actuating arm for said blast valve having a cam portion formed thereon, trip-free means comprising a releasable member having a cam portion formed thereon for engaging the cam portion on said actuating arms to operate said blast valve, means operatively relating said releasable member to said movable contact, closing means at all times connected to said releasable member for operating said movable contact to closed position, and a trip device operable to release said releasable member to effect separation of said contacts and opening of said blast valve irrespective of the position of said closing means.

22. In a circuit interrupter of the gas-blast type, a stationary contact, a movable contact separable from said stationary contact to establish an are, a source of fluid under pressure, a blast valve for controlling a blast of fluid to effect extinction of said arc, cam means associated with said blast valve, closing means operable to move said movable contact to closed position, a tripfree mechanism comprising a releasable member at all times connected to said closing means and to said movable contact, cam means on said releasable member for engaging the cam means associated with said blast valve to operate said blast valve, spring means biasing said releasable member in opening direction, and a trip device operable to release said releasable members to effect opening of said contacts and opening of said blast valve irrespective of the position of said closing means.

HOWARD M. WILCOX. RAYMOND H. LEITZEL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,282,154 Bakken May 5, 1942 1,318,784 Mahoney et al Oct. 14, 1919 1,757,643 MacNeill May 6, 1930 2,272,380 Ludwig et al. Hum Feb. 10, 1942 2,325,949 Gayer Aug. 3, 1943 

